From: Robert Klemme <shortcutter@...>
Date: 2007-05-06T19:10:04+09:00
Subject: Re: How can I output an object/variable's name?

On 05.05.2007 23:19, John Joyce wrote:
> 
> On May 6, 2007, at 6:06 AM, Robert Dober wrote:
> 
>> On 5/5/07, John Joyce <dangerwillrobinsondanger@gmail.com> wrote:
>>> Suppose I have an object :
>>>
>>> a = 3
>>>
>>> I want to output the name a and the contents 3
>>> Outputing the contents is no problem.
>>> Is  there a method to output the name of the variable (object)
>>
>> No there is no way to output the name of a variable as a variable is
>> one of the view concepts in Ruby that are not directly accessible from
>> inside Ruby.
>> When it comes to objects things change of course, some objects have
>> name properties as e.g. classes
>>
>> irb(main):002:0> A=Class.new
>> => A
>> irb(main):003:0> A.name
>> => "A"
>> But be aware that it is the object and not the constant referring to
>> it who has the name, as one can easily see...
>> irb(main):007:0* b = Class.new
>> => #<Class:0xb7d9ce54>
>> irb(main):008:0> b.name
>> => ""
>> irb(main):009:0> C = b
>> => C
>> irb(main):010:0> C.name
>> => "C"
>> irb(main):011:0> b.name
>> => "C"
>>
>> this is maybe a little bit confusing but that is what ruby does when a
>> class object is assigned to a constant.
>>
>> Robert
> Thanks Robert, but...
> 
> That is totally confusing.
> So what you are saying is that some objects have names and some do not.
> Since everything (almost) is an object, which objects or which classes 
> would have names?

No, he is saying that there are classes whose instances have a property 
called "name".  But this has absolutely nothing to do with variable 
names.  If you think about it for a moment, it does not really make 
sense to want to get a variable name from an object.  Consider

a = b = Object.new

Now, there is just one instance - which "name" would you like to get?

> Oh, maybe I should go to bed. it's 6:20am here in Japan.

Sleep always helps. :-)

> What about injecting my own name properties into a class, could I do 
> this type of injection in a code block?

I am not sure what you mean by "injection".  But you can set instance 
variables - if you wish so.  But you might run into trouble if you 
overwrite a property that's crucial for the instance.  Look at 
instance_variables and *set and *get.

Kind regards

	robert